Ammonium cyamelurates: synthesis and crystalline structures

Abstract

Contradictory literature on the alkali-assisted exfoliation of the melon and searching for the best precursors for different heptazine derivative synthesis led us to the synthesis of two cyameluric acid salts, (NH4)2[C6N7O3H] (ECN3) and (NH4)2(H9O4)[C6N7O3] (ECN5). These salts were characterized by single-crystal X-ray diffractometry for the first time. Ammonium cations bind C6N7O3H2− anions (ECN3) by means of Coulombic compression and hydrogen bonds. In ECN5, stability of the columns consisting of C6N7O33− anion triads is provided by Coulombic compression and hydrogen bonds between anions, ammonium cations, and hydroxonium (H9O4+). The planar cyamelurate anions of one triad are located strictly above each other with the distance of 3.710(3) Å between the neighbor anions. Each triad is twisted relative to the adjacent one by an angle of 60° and is distant by 3.605(3) Å.

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Acknowledgements

This work (XRD study) was supported in part by the M. V. Lomonosov Moscow State University Program of Development. The authors are grateful to V. V. Chernyshev for his kind assistance with the XRD experiment.